The present invention relates to a fork-lift truck for selectively displacing a load forward or sideways, comprising: a horizontal, substantially U-shaped frame; a lifting mechanism for carrying the load, wherein legs of the frame extend along the lifting mechanism; and wheels on the legs which are connected to the legs via rotating mechanisms for driving and which are rotatable on a substantially upward axis between positions corresponding with sideways and forward movements of the fork-lift truck, wherein flexible power supply and control lines run with slack through the legs to the wheels.
Such fork-lift trucks are generally known, wherein the power supply and control lines are connected to for instance drive motors for the wheels, the rotating mechanism, a support foot for energizing with a cylinder etc. Flexible lines are preferred in view of the high cost in respect of both work and material and other factors. The slack in the power supply and control lines is essential during rotation of the rotating mechanism to maintain the connection to the motor and/or the rotating mechanism etc. at each angular displacement of the rotating mechanism. In any angular position hereof corresponding with substantially forward and/or sideways movement the wheels can herein be driven, varied in position and so on.
The known fork-lift trucks have a number of drawbacks. These power supply and control lines are normally laid loosely through the legs of the frame. When released, the necessary slack in the power supply and control lines is herein taken up in sliding manner in the interior of the legs. Release of the slack is understood to mean that the wheels are placed in a position wherein, in the case of an angular displacement of the position of the wheels wherein a greater length of the power supply and control lines is necessary to maintain the connection, the slack becomes available to provide the extra length herefor.
The sliding take-up of the slack in the legs results in wear of the power supply and control lines. In the known fork-lift trucks the lines have to be replaced frequently or covered with wear-resistant material, which not only has an adverse effect on the flexibility of the lines but also on production costs. Sufficient internal space is further necessary in the legs of the frame to provide room for the slack of the power supply and control lines. It is hereby necessary in the known fork-lift trucks to use very thick legs for the frame, and this involves high costs. The use of legs with sufficient internal space to take up the slack therein further results in limitations in respect of the tyre sizes which can be used, in particular the widths hereof. The greatest possible distance between the legs is desired to enable placing therebetween of the widest possible lifting mechanism, for instance a fork mechanism. Maximum widths of fork-lift trucks are usually regulated by law. For determined fields of application, for instance in the use of the fork-lift truck on sand, associated tyre sizes, in particular widths, are required. The need for a large internal space in the legs therefore reduces the space available between the legs and/or the width of the fork-lift truck and/or the possible width of the tyres. All available internal space is further required to take up the slack, so that there is no room in the legs or extensions thereof for a rotating mechanism designed for instance as hydraulic cylinder. This must therefore be mounted outside the internal space, i.e. on or adjacently of or under the legs, which is unfavourable due to the vulnerability thereof and also in applications wherein the fork-lift truck is suspended on the rear of a truck. In this latter use, space available in the truck is lost due to the cylinder for suspending the fork-lift truck, or the free space under a fork-lift truck suspended from the truck becomes small.
The present invention has for its object to obviate or at least reduce the above stated and other problems of the known fork-lift truck, for which purpose the fork-lift truck according to the present invention is distinguished from the known fork-lift trucks in that it further comprises: a bending mechanism at each of the legs for bending the power supply and control lines without frictional contact with the interior of the legs during release of the slack. Wear of the power supply and control lines is avoided according to the invention and it is possible to suffice with a small internal dimension of the legs of the frame, with the result of thinner legs and more space available for the greatest possible distance between the legs and/or a tyre size, in particular the width thereof, depending on the field of application. A rotating mechanism can also be accommodated in the legs or extensions thereof.
Many embodiments of the bending mechanism are possible within the scope of the invention. A number of possibilities are defined in the sub-claims. The bending mechanism can for instance comprise at least one clamp connected to the rotating mechanism. The clamp defines the bending shape into which an associated flexible power supply and control line is placed when the slack is released. This is an advantageous embodiment which is readily realized. When moving in the direction of the leg the curve for instance approaches the direction parallel to a tangent of a turning circle of the rotating mechanism.
Additionally or alternatively, the bending mechanism can comprise at least one guide connected to the leg. During rotation of the rotating mechanism the associated flexible power supply and control line can be carried into a curvature which, when moving in the direction of the leg, approaches a direction parallel to a tangent on a turning circle of the rotating mechanism, although other forms of the bending curve are possible.